The Collaborative International Dictionary of English v.0.48:

Lues \Lu"es\, n. [L.] (Med.)
   1. Disease, especially of a contagious kind. [archaic]
      [1913 Webster]

   2. syphilis; -- called also Lues venerea.
      [1913 Webster +PJC]

   Lues venerea, syphilis; -- called also simply lues.
      [1913 Webster]

WordNet (r) 3.0 (2006):

lues
    n 1: a common venereal disease caused by the treponema pallidum
         spirochete; symptoms change through progressive stages; can
         be congenital (transmitted through the placenta) [syn:
         syphilis, syph, pox, lues venerea, lues]